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Dramatically reduced lattice thermal conductivity of Mg_2Si thermoelectric material from nanotwinning

Li, Guodong and He, Jiangang and An, Qi and Morozov, Sergey I. and Hao, Shiqiang and Zhai, Pengcheng and Zhang, Qingjie and Goddard, William A., III and Snyder, G. Jeffrey (2019) Dramatically reduced lattice thermal conductivity of Mg_2Si thermoelectric material from nanotwinning. Acta Materialia, 169 . pp. 9-14. ISSN 1359-6454. doi:10.1016/j.actamat.2019.02.041.

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Tuning phonon transport to reduce the lattice thermal conductivity (κ_L) is crucial for advancing thermoelectrics (TEs). Traditional strategies on κ_L reduction focus on introducing scattering sources such as point defects, dislocations, and grain boundaries, that may degrade the electrical conductivity and Seebeck coefficient. We suggest here, a novel twin boundary (TB) strategy that can decrease the κ_L of Mg_2Si by ∼90%, but which may not degrade the electrical properties significantly. We validate this suggestion using density functional theory (DFT). We attribute the mechanism of TB induced κ_L reduction to (i) the lower phonon velocities and larger Grüneisen parameter, (ii) “rattling” of the Mg--Mg pair induced soft acoustic and optical modes, (iii) shorter phonon lifetime and higher phonon scattering rate. We predict that the size of nanotwinned structure should be controlled between 3 nm and 100 nm in the Mg2Si matrix for the most effective κ_L reduction. These results should be applicable for other TE or non TE energy materials with desired low thermal conductivity, suggesting rational designs of high-performance Mg_2Si TE materials with low κ_L for the energy conversion applications.

Item Type:Article
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URLURL TypeDescription
Li, Guodong0000-0002-4761-6991
An, Qi0000-0003-4838-6232
Morozov, Sergey I.0000-0001-6226-5811
Zhai, Pengcheng0000-0002-5737-5220
Goddard, William A., III0000-0003-0097-5716
Snyder, G. Jeffrey0000-0003-1414-8682
Alternate Title:Dramatically reduced lattice thermal conductivity of Mg2Si thermoelectric material from nanotwinning
Additional Information:© 2019 Acta Materialia Inc. Published by Elsevier Ltd. Received 12 February 2019, Revised 25 February 2019, Accepted 25 February 2019, Available online 1 March 2019. This work is partially supported by the 111 Project of China under Project no. B07040. Q.A. and W.A.G were supported by the National Science Foundation CMMI program under grant no. 1727428. S.M. is thankful for the support by Act 211 Government of the Russian Federation, under No. 02.A03.21.0011 and by the Supercomputer Simulation Laboratory of South Ural State University [57].
Funding AgencyGrant Number
111 Project of ChinaB07040
Russian Federation02.A03.21.0011
South Ural State UniversityUNSPECIFIED
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Record Number:CaltechAUTHORS:20190301-101134456
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Official Citation:Guodong Li, Jiangang He, Qi An, Sergey I. Morozov, Shiqiang Hao, Pengcheng Zhai, Qingjie Zhang, William A. Goddard, G. Jeffrey Snyder, Dramatically reduced lattice thermal conductivity of Mg2Si thermoelectric material from nanotwinning, Acta Materialia, Volume 169, 2019, Pages 9-14, ISSN 1359-6454, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93391
Deposited By: Tony Diaz
Deposited On:01 Mar 2019 18:21
Last Modified:16 Nov 2021 16:57

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